A jaunt into the future, we see the world more than 6000 years down the line, long after the events that changed Earth with Equestria's intervention. A surviver seeks out information on those they lost in the chaos. It leads to the Arbor Society.
In the wake of losing almost all of humanity, a road trip is planned. Spending the apocalypse alone isn't fun, especially as a horse. This is my telling of how we went from the Rocket City to the Rockies.